Low cost redundant AC to DC power supply

• US 6,630,753 B2
• Filed: 10/29/2001
• Issued: 10/07/2003
• Est. Priority Date: 10/29/2001
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Ho, Diep N., Oak, Vijay V., Malik, Randhir S.
• Primary Examiner(s): STERRETT, JEFFREY L
• Application Number:
  US10/016,555
• Publication Number:
  US 20030080625A1
• Time in Patent Office: 708 Days
• Field of Search: 307/64, 307/80, 307/85, 307/86, 307/87, 363/69, 363/70, 363/126
• US Class Current: 307/64
• CPC Class Codes: H02J 9/061 for DC powered loads

Abstract

The power supply in accordance with the present invention provides AC redundancy while also preventing voltages from multiple AC voltage sources from adding at a common node. The adding of voltages is avoided by ensuring that only one AC voltage source at a time is providing the voltage at the output. Even if the other AC voltage sources are connected afterwards, these later AC voltage source are prevented from providing power at the output. In addition, diodes prevent current from back flowing to the AC voltage sources which are not supplying power to the output. Because the power supply in accordance with the present invention neither uses redundant AC to DC power supplies from independent AC voltage sources, nor does it use a costly transfer switch, the power supply in accordance with the present invention is more cost effective than conventional redundant power supplies.

Claims

1. A circuit, comprising:

a first opto-coupler coupled to a first voltage source;

a first set-reset latch coupled to the first opto-coupler;

a first resistor coupled to the first opto-coupler and the first set-reset latch;

a first silicon controller rectifier (SCR) coupled to the first set-reset latch, the first resistor, the first voltage source, and a load;

a first diode coupled to the first voltage source, the first opto-coupler, and the load;

a second opto-coupler coupled to a second voltage source and across the first resistor;

a second set-reset latch coupled to the second opto-coupler;

a second resistor coupled to the second opto-coupler, the second set-reset latch, and the second voltage source, wherein the first opto-coupler is coupled across the second resistor;

a second SCR coupled to the second set-reset latch, the second resistor, the second voltage source, and the load; and

a second diode coupled to the second voltage source, the second opto-coupler, and the load.

2. The circuit of claim 1, further comprising:

a first bridge rectifier coupled to the first voltage source; and

a second bridge rectifier coupled to the second voltage source.

3. The circuit of claim 2, wherein the first opto-coupler is coupled to a node of the first bridge rectifier and the first resistor.

4. The circuit of claim 2, wherein the second opto-coupler is coupled to the second bridge rectifier and the second resistor.

5. The circuit of claim 1, wherein the first resistor is coupled to first opto-coupler, an S pin of the first set-reset latch, the voltage source, and a cathode of the first SCR.

6. The circuit of claim 1, wherein a gate of the first SCR is coupled to a Q pin of the first set-reset latch, an anode of the first SCR is coupled to the load, and the cathode of the first SCR is coupled to the first resistor and the first voltage source.

7. The circuit of claim 1, wherein an anode of the first diode is coupled to the first voltage source and a cathode of the first diode is coupled to the load.

8. The circuit of claim 1, further comprising a third resistor coupled to the first voltage source, the first opto-coupler, and an anode of the first diode.

9. The circuit of claim 1, further comprising:

a first capacitor coupled to a gate of the first SCR and a cathode of the first SCR.

10. The circuit of claim 1, wherein an S pin of the first set-reset latch is coupled to the first opto-coupler and a Q pin of the first set-reset latch is coupled to a gate of the first SCR.

11. The circuit of claim 1, wherein an S pin of the second set-reset latch is coupled to the second opto-coupler and a Q pin of the second set-reset latch is coupled to a gate of the second SCR.

12. The circuit of claim 1, wherein the second resistor is coupled to the second opto- coupler, an S pin of the second set-reset latch, the second voltage source, and a cathode of the second SCR.

13. The circuit of claim 1, wherein a gate of the second SCR is coupled to a Q pin of the second set-reset latch, an anode of the second SCR is coupled to the load, and a cathode of the second SCR is coupled to the second resistor and the second voltage source.

14. The circuit of claim 1, wherein an anode of the second diode is coupled to the second voltage source and a cathode of the second diode is coupled to the load.

15. The circuit of claim 1, further comprising a fourth resistor coupled to the second voltage source, the second opto-coupler, and an anode of the second diode.

16. The circuit of claim 1, further comprising:

a second capacitor coupled to a gate of the second SCR and a cathode of the second SCR.

17. A circuit, comprising:

a first bridge rectifier comprising a first, second, third, and fourth nodes, wherein the first and third nodes of the first bridge rectifier are coupled to a first voltage source;

a first resistor coupled to the second node of the first bridge rectifier;

a first opto-coupler comprising a first diode and a first transistor, wherein an anode of the first diode is coupled to the first resistor;

a first set-reset latch comprising an S pin and a Q pin, wherein the S pin is coupled to a cathode of the first diode;

a second resistor coupled to the cathode of the first diode, the S pin of the first set-reset latch, and the fourth node of the first bridge rectifier;

a first SCR, wherein a gate of the first SCR is coupled to the Q pin of the first set-reset latch, a cathode of the first SCR is coupled to the second resistor and the fourth node of the first bridge rectifier, and an anode of the first SCR is coupled to a load;

a second diode, wherein an anode of the second diode is coupled to the second node of the first bridge rectifier and the first resistor, and a cathode of the second diode is coupled to the load;

a second bridge rectifier comprising a first, second, third, and fourth nodes, wherein the first and third nodes of the second bridge rectifier are coupled to a second voltage source;

a third resistor coupled to the second node of the second bridge rectifier;

a second opto-coupler comprising a third diode and a second transistor, wherein an anode of the third diode is coupled to the third resistor, wherein the second transistor is coupled across the second resistor;

a second set-reset latch comprising an S pin and a Q pin, wherein the S pin of the second set-reset latch is coupled to a cathode of the third diode;

a fourth resistor coupled to the cathode of the third diode, the S pin of the second set-reset latch, and the fourth node of the second bridge rectifier, wherein the first transistor is coupled across the fourth resistor;

a second SCR, wherein a gate of the second SCR is coupled to the Q pin of the second set-reset latch, a cathode of the second SCR is coupled to the fourth resistor and the fourth node of the second bridge rectifier, and an anode of the second SCR is coupled to the load; and

a fourth diode, wherein an anode of the fourth diode is coupled to the second node of the second bridge rectifier and the third resistor, and a cathode of the fourth diode is coupled to the load.

18. A circuit, comprising:

a first bridge rectifier coupled to a first voltage source;

a first opto-coupler coupled to the first bridge rectifier, wherein the first opto-coupler comprises a first diode and a first transistor;

a first set-reset latch coupled to the first diode;

a first resistor coupled to the first diode, the first set-reset latch, and the first bridge rectifier;

a first SCR coupled to the first set-reset latch, the first resistor, the first bridge rectifier, and a load;

a second diode coupled to the first bridge rectifier, the first opto-coupler, and the load;

a second bridge rectifier coupled to a second voltage source;

a second opto-coupler coupled to the second bridge rectifier, wherein the second opto-coupler comprises a third diode and a second transistor, wherein the second transistor is coupled across the first resistor;

a second set-reset latch coupled to the third diode;

a second resistor coupled to the third diode, the second set-reset latch, and the second bridge rectifier, wherein the first transistor is coupled across the second resistor;

a second SCR coupled to the second set-reset latch, the second resistor, the second bridge rectifier, and the load; and

a fourth diode coupled to the second bridge rectifier, the second opto-coupler, and the load.

19. The circuit of claim 18, wherein the first voltage source is coupled to a first and second node of the first bridge rectifier.

20. The circuit of claim 18, wherein an anode of the first diode is coupled to a node of the first bridge rectifier and a cathode of the first diode is coupled to the first resistor.

21. The circuit of claim 18, wherein an S pin of the first set-reset latch is coupled to a cathode of the first diode and a Q pin of the first set-reset latch is coupled to a gate of the first SCR.

22. The circuit of claim 18, wherein the first resistor is coupled to a cathode of the first diode, an S pin of the first set-reset latch, a node of the first bridge rectifier, and a cathode of the first SCR.

23. The circuit of claim 18, wherein a gate of the first SCR is coupled to a Q pin of the first set-reset latch, an anode of the first SCR is coupled to the load, and the cathode of the first SCR is coupled to the first resistor and a node of the first bridge rectifier.

24. The circuit of claim 18, wherein an anode of the second diode is coupled to a node of the first bridge rectifier and a cathode of the second diode is coupled to the load.

25. The circuit of claim 18, further comprising a third resistor coupled to a node of the first bridge rectifier, an anode of the first diode, and an anode of the second diode.

26. The circuit of claim 18, further comprising:

a first capacitor coupled to a gate of the first SCR and a cathode of the first SCR.

27. The circuit of claim 26, further comprising:

a second capacitor coupled to a gate of the second SCR and a cathode of the second SCR.

28. The circuit of claim 18, wherein an anode of the third diode is coupled to a node of the second bridge rectifier and a cathode of the third diode is coupled to the second resistor.

29. The circuit of claim 18, wherein an S pin of the second set-reset latch is coupled to a cathode of the third diode and a Q pin of the second set-reset latch is coupled to a gate of the second SCR.

30. The circuit of claim 18, wherein the second resistor is coupled to a cathode of the third diode, an S pin of the second set-reset latch, a node of the second bridge rectifier, and a cathode of the second SCR.

31. The circuit of claim 18, wherein a gate of the second SCR is coupled to a Q pin of the second set-reset latch, an anode of the second SCR is coupled to the load, and a cathode of the second SCR is coupled to the second resistor and a node of the second bridge rectifier.

32. The circuit of claim 18, wherein an anode of the fourth diode is coupled to a node of the second bridge rectifier and a cathode of the fourth diode is coupled to the load.

33. The circuit of claim 18, further comprising a fourth resistor coupled to a node of the second bridge rectifier, an anode of the third diode, and an anode of the fourth diode.

34. The circuit of claim 18, wherein an anode of the fourth diode is coupled to the second bridge rectifier and a cathode of the fourth diode is coupled to the load.

35. The circuit of claim 18, wherein the second voltage source is coupled to a first and second node of the second bridge rectifier.